The present invention relates to methods and apparatuses for processing drilling fluids used in oilfield well drilling and, more particularly, to a method and an apparatus for homogenizing drilling fluid in an open-loop process. In general, the method and apparatus for homogenizing drilling fluid dissolve polymers and other additives to homogenize drilling fluid in an effort to eliminate clogging within the closed-loop designed drilling fluid system while simultaneously increasing the throughput of the homogenized drilling fluid for use in the closed-loop designed drilling fluid system.
In the oilfield industry, when drilling a well, a lubricant termed xe2x80x9cdrilling fluidxe2x80x9d or xe2x80x9cdrilling mudxe2x80x9d (hereinafter referred to as xe2x80x9cdrilling fluidxe2x80x9d) is used. The major functions of the drilling fluid are to: (1) remove the drilled cuttings from the wellbore hole; (2) control the subsurface pressures; (3) cool and lubricate the bit and drill pipe; (4) prevent the walls of the wellbore hole from caving; (5) release the drilled cuttings and sands at the wall""s surface; (6) prevent damaging effects to the formation (subterranean earth) penetrated; (7) allow maximum information from the formation penetrated; (8) suspend the cuttings and weight material when circulation of the drill is stopped; and (9) help suspend the weight of the drill string and casing, all of which are described in xe2x80x9cFUNCTIONS OF DRILLING FLUIDS AND TESTING PROCEDURES,xe2x80x9d in Applied Mud Technology, Chapter 1, pages 3-4, by IMCO SERVICES (A Division of HALLIBURTON Company). Moreover, drilling fluid, as described in the Fourth Edition of xe2x80x9cA Primer of Oilwell Drilling,xe2x80x9d by Ron Baker, copyright 1979, page 47, xe2x80x9cprovides the first line of defense against blowouts.xe2x80x9d
There are numerous formulas for the formulation of the drilling fluid some of which are water-based and others of which are oil-based or synthetic drill fluids. Depending on the subterranean geology of the earth, such as when deep sea drilling, a water-based drilling fluid is used for part of the drilling operation and thereafter, an oil-based drilling fluid is used. Moreover, depending on the subterranean geology of the earth, the water-based drilling fluid may be altered during the drilling operations. For example, when drilling a wellbore hole, a 2400 ft. subterranean section may require a drilling fluid with a 10% salt content while, just below, another subterranean section of 2000 ft. may require a drilling fluid with a much higher salt content.
A water-based drilling fluid may include, without limitation: (1) water (such as, salt water or fresh water), the drilling fluid base, (2) a viscosifier polymer, such as, XCD Polymer (a biopolymer), available from a Business Unit of M-I L.L.C., for assisting in suspending cuttings; (3) a fluid loss polymer, such as, DRISPAC Polymer (a cellulosic polymer), available from a Business Unit of M-I L.L.C., for forming a filter cake around the welbore hole wall surface; (4) a stabilization polymer, such as, Poly-Plus RD (an acrylic polymer), available from a Business Unit of, M-I L.L.C.; and, (5) other additives. Examples of other additives in the drilling fluid are (1) for the control of the salt content, sodium chloride, available from by a Business Unit of M-I L.L.C.; and, (2) for water treatment, soda ash (sodium carbonate), available from a Business Unit of M-I L.L.C. to treat out calcium which may be present in water. Nevertheless, there are numerous alternatives which can be substituted for the above identified polymers and additives, as well as, other polymers and/or additives which may be need to create the drilling fluid for the specific subterranean geology of the earth. For example, the MAYCO MAPP(trademark) polymer, as described in xe2x80x9cMAYCO MAPP(trademark) MAYCO All Purpose Polymer,xe2x80x9d from the web site (www.maycowellchem.com), can be used in the same manner as DRISPAC. Other formate brines are described in xe2x80x9cHYDRO CHEMICALS (UK) LTD-DRILLING AND COMPLETION FLUIDS,xe2x80x9d from the web site (www.offshore-techonogy.com).
U.S. Pat. No. 4,867,256, issued to Snead, entitled xe2x80x9cINJECTION OF POLYMER CHEMICALS INTO DRILLING MUDxe2x80x9d discloses various functions and characteristics of drilling muds and is incorporated herein by reference as if set forth in full below. However, the invention of the Snead patent is primarily focused on introducing a liquid water loss controlling polymer into the suction of a main circulating mud pump rather than by pouring the liquid chemical into the open collar of a drill pipe joint.
U.S. Pat. No. 4,462,470, issued to Alexander, entitled xe2x80x9cEXTRUSION OF BENTONITE CLAY FOR FLUID LOSS REDUCTION IN DRILLING FLUIDS,xe2x80x9d discloses general principles of drilling fluid. However, the Alexander invention is related to extruding bentonite clay into clay pellets having a majority of oriented clay platelets. The output of the mill used for extruding the bentonite clay includes a rotating wiper blade, scraping blade or cutter positioned on the interior side of apertured surface of a die plate to extrude bentonite clay into clay pellets having a majority of oriented clay platelets. The mill is used to create bentonite pellets which are dried and ground. Alexander does not teach using the mill in the processing of drilling fluids.
Referring now to FIG. 1, a general diagram of a conventional closed-loop designed drilling fluid system 1 is shown and described, in brief, in the Fourth Edition of xe2x80x9cA Primer of Oilwell Drilling,xe2x80x9d by Ron Baker, copyright 1979, pages 42-46. It should be noted that the closed-loop designed drilling fluid system 1 is designed to be closed-loop in that the drilling fluid flowing therein is adapted to be recovered and recycled through the closed-loop designed drilling fluid system 1. However, during drilling operations, drilling fluid is inherently lost from the closed-loop designed drilling fluid system 1 and, thus, may need to be replenished.
The closed-loop designed drilling fluid system 1 includes at least one holding tank T1, an active tank T2, and at least one reclamation tank T3 which stores the initial mixture of the drilling fluid, the processed drilling fluid, and the recycled drilling fluid, respectively. As can be appreciated, the closed-loop designed drilling fluid system 1 begins with hopper H1 having the poured contents flowing to the holding tank T1 and ends with the at least one reclamation tank T3. The closed-loop designed drilling fluid system 1 includes further includes suction line SL, pumping station PS, discharge line DL, stand pipe SP, rotary hose RH, wellbore hole WH, drilling fluid return line RL, and shale shaker SS. Finally, the kelly K, coupled to the rotary hose RH, the drill pipe DP and drill bit DB (collectively, the xe2x80x9cdrilling unitxe2x80x9d) are coupled in series with the closed-loop designed drilling fluid system 1 to complete the closed-loop.
During drilling operations, the drilling fluid is pumped from the active tank T2 via suction line SL, through the pumping station PS via filter/screen FS to the discharge line DL, up through the stand pipe SP, through the rotary hose RH, down the kelly K and drill pipe DP and out though drill bit DB. As the drilling fluid exists through the drill bit DB, the drilling fluid moves upward in the wellbore hole WH to the drilling fluid return line RL and continues to flow over shale shaker SS. The shale shaker SS includes a mesh M positioned over the at least one reclamation tank T3 which allows the drilling fluid to be poured into the at least one reclamation tank T3. Thereby, the drilling fluid is recycled for re-circulation through the closed-loop designed drilling fluid system 1. The above description of the closed-loop designed drilling fluid system 1 is of course rather simplistic. While not shown, further included in the closed-loop designed drilling fluid system 1 are desilters, desander and/or degasser for filtering fine silt, sand and gas from the drill fluid before re-circulation.
In a holding (mixing) tank T1 of the drilling rig, having a storage capacity of, for example, 10 barrels to 500 barrels, a mixture of water (such as, saltwater or freshwater), polymer(s) and other additives are added together via hopper H1. The polymer(s) and other additives are generally in powder form (hereinafter referred to as xe2x80x9cgranulesxe2x80x9d). As the mixture (drilling fluid) is formed, the polymers and additives begin to dissolve in the water and/or mixture of water and additives. As the polymers dissolve, a viscous slim-like drilling fluid is created. However, as the polymers dissolve and the slim-like drilling fluid created, globs of undissolved polymer granules, especially, the fluid loss polymer granules, are formed much like the result of flour added to water.
In general, non-homogenized drilling fluid, upon inspection, includes suspended slim-like strings, globs of undissolved polymer granules which are, typically, of the fluid loss polymer such as, DRISPAC Polymer, and other particulate matter. While the undissolved granules of the globs are, generally, the powder of the fluid loss polymer such as, DRISPAC Polymer, other powders of the additives and/or other polymers may likewise become entrapped in such globs as the globs are formed. The undissolved polymer granules of the globs are entrapped since the globs have resiliently deforming and rapidly resealing capabilities which, in general, result when the undissolved polymer granules contact the water.
The fluid loss parameter of the drilling fluid is designed to provide a thin but tough filter cake or barrier circumferentially around the wellbore along the walls of the formation to retard invasion of the drilling fluid. It is desirable to use additives and polymers which serve to improve the toughness and firmness of the filter cake or barrier created by the drilling fluid. It should be noted, the toughness and firmness are relative to an environment in which drilling via a rotating drill bit is being performed. Thus, as can be appreciated, any additive or polymer which is not dissolved in the mixture of the drilling fluid compromises the effectiveness of the drilling fluid to perform the major functions, set forth above. Filtration or fluid loss and adverse effects of an excessive filtration rate are described in xe2x80x9cFILTRATION,xe2x80x9d of Applied Mud Technology, Chapter 4, pg. 9, by IMCO SERVICES (A Division of HALLIBURTON Company), which is incorporated herein by reference. As described, an adverse effect of an excessive filtration rate includes caving of the wellbore hole, which is highly undesirable, as a result of high water-loss muds.
More importantly, that which serves to create such fluid loss parameter (fluid loss polymer, such as, DRISPAC polymer) so that the filter cake is tough and firm, when dissolving creates resiliently deforming and rapidly resealing globs of sealed undissolved polymer granules in the slim-like drilling fluid.
As can be appreciated, there is a continuing need in the drilling industry for the slim-like drilling fluid, having these globs, to be processed to reduce these globs in order to dissolve the undissolved polymer granules to achieve the viscosity and fluid loss parameters of the drilling fluid and decrease the size of the globs so that the drilling fluid does not clog the closed-loop designed drilling fluid system""s filter/screen FS at the pumping station PS. In general, the closed-loop designed drilling fluid system""s filter/screen FS may include pores of approximately xc2xc of an inch.
Typically, a closed-loop system (hereinafter a xe2x80x9cClosed-Loop Preprocessorxe2x80x9d) is used to dissolve and mix the drilling fluid to ready it for use in the closed-loop designed drilling fluid system 1. The prior art Closed-Loop Preprocessors have proven to be unsatisfactory. One known time-consuming system can reduce the glob size to an acceptable level after cycling the drilling fluid in such a Closed-Loop Preprocessor three (3) times. However, such acceptable level is in no way non-clogging compared to my invention.
The known Closed-Loop Preprocessors utilize a special pump (such as, a xe2x80x9cPoly Gatorxe2x80x9d) and a recycling tank. The mixture from the rig""s holding tank is pumped into a centrifugal pump operated by, for example, a 100-horsepower motor. The centrifugal pump includes a propeller which mixes and beats the drilling fluid in an effort to homogenize the drilling fluid and to dissolve, and thus partially reduce, the globs of the undissolved polymer(s) granules therein. The outlet of the centrifugal pump has an orifice which is partially blocked to minimize the flow of the drilling fluid therethrough to increase the processing time within the pump. A large apertured screen is also used within the pump chamber to filter the drilling fluid.
The drilling fluid pumped out of the outlet is sent to the recycling tank wherein the drilling fluid is checked visually (since the fluid is essentially clear) to estimate the size of the globs remaining. As the globs are reduced, the polymer granules are dissolved until an acceptable glob size within the drilling fluid is achieved. Typically, the drilling fluid must be recycled through the Closed-Loop Preprocessors at least two (2) more times to achieve an acceptable glob size. Essentially, all the drilling fluid in the Closed-Loop Preprocessor is recycled. Thus, the Closed-Loop Preprocessor cannot provide a continuous xe2x80x9con demandxe2x80x9d supply of drilling fluid. Instead, the Closed-Loop Preprocessor delays the flow of the drilling fluid to the closed-loop designed drilling fluid system until an acceptable glob size is achieved. Ink general, the total effective throughput of a Closed-Loop Preprocessor is significantly less than that of my invention since recycling is required for the Closed-Loop Preprocessor and recycling is not required for my invention.
It should be further noted, that when using a drilling fluid preprocessed by said Closed-Loop Preprocessor, drilling operations are halted numerous times so that the clogged filter/screen FS of the closed-loop designed drilling fluid system 1 can be cleaned and unclogged. Every time, drilling operations are halted, on the average, an hour is lost at a cost of approximately $8000-$10,000 per hour. It is estimated that approximately $50,000 are lost due to clogging of the filter/screen FS for a 4 or 5-day drilling operation and increased for longer drilling operations.
One of the biggest challenges in dissolving the undissolved polymer granules in the globs is that the globs stretch and deform when beaten, such as, by a propeller. As the globs of undissolved polymer granules are hit or wacked, the resiliently deformable and rapidly resealable globs, entrapping and sealing the undissolved polymer granules, are not necessarily penetrated but instead deformed and/or stretched. Thus, the polymer granules remain entrapped in such resiliently deformable and rapidly resealable glob.
Since the known Closed-Loop Preprocessors are time consuming and have an inadequate throughput, typically, for offshore drilling, such as deep sea drilling, a start-up load of drilling fluid is pre-processed onshore and delivered to the offshore drilling rig site via a large (250 ft. plus) boat. Thereby, any delays in the initial drilling operations due to the processing of a sufficient load of the drilling fluid to acceptable levels are essentially eliminated. Not only are there costs associated with the transport of the initial start-up load of the processed drilling fluid, sea water or fresh water(the base) used to mix the drilling fluid may need to be hauled onshore for the processing of the drilling fluid. Depending on the salt content of the sea water and, especially, fresh water, hauled onshore and the necessary salt content of the drilling fluid, 2000 lbs. or more of salt for approximately twenty (20) barrels may need to be added for the initial start-up load of the drilling fluid.
The costs associated with the preprocessing of the drilling fluid, the transport of the pre-processed drilling fluid to the offshore drilling site and the costs associated with hauling the sea water or fresh water onshore for the initial load of the drill fluid still does not compare with the hourly costs associated with an operational drilling rig site. Nevertheless, while great effort is taken for the creation of the initial start-up load of the drill fluid, such drilling fluid, oftentimes, clogs the closed-loop designed drilling fluid system""s filter/screen FS. Thereby the drilling operations must be shutdown so that the closed-loop designed drilling fluid system""s filter/screen FS can be cleaned and unclogged.
Even though an initial start-up load is created onshore and transported to the drilling rig site so that drilling operations are essentially not delayed and thus the cost of an operational rig site reduced, at times there is still an inadequate supply of drilling fluid during the drilling operations. Depending on the rig, the drilling operation and the depth of the wellbore hole, 100 gallons/hr. to a few 1000 gallons/hr. of the drilling fluid may be required. If there is an insufficient supply of the drilling fluid, the drilling rig must be stopped until the supply of the drilling fluid is available. At an average cost of approximately $210,000 a day for an operational offshore drilling rig site, any downtime of the drilling operations is very costly and, thus, highly undesirable.
Nevertheless, the required drilling fluid for drilling operations is essentially variable since there are numerous unknown factors, such as, without limitation, bad weather delaying the arrival of additional pre-mixed drilling fluid from onshore and/or excessive drilling fluid circulation losses.
In an effort to minimize the downtime of the drilling operations in such instances, on occasion, if the supply of the drilling fluid is unavailable or insufficient, the drilling fluid having an unacceptable dissolved percentage is used which tends to clog the filter/screen FS. Thereby, the drilling operations must be shutdown and the filter/screen FS cleaned.
Another drawback with the present processed drilling fluid is that the drilling fluid clogs the shale shaker SS of the closed-loop designed drilling fluid system 1 thereby preventing the drilling fluid from entering the at least one reclamation tank T3. The drilling fluid sheens over the pores of the mesh M of shale shaker SS. Thereby, the drilling fluid is obstructed from filtering through the pores of the mesh M. More specifically, xe2x80x9cfish eyesxe2x80x9d (clear globs) are readily visible over the mesh of the shale shaker SS. As is apparent, the drilling fluid sheen and xe2x80x9cfish eyesxe2x80x9d over the mesh of the shale shaker SS prevents the drilling fluid from being filtered through the mesh and, thereafter, recycled. Instead, the drilling fluid spills over to the slide S, used for the removal of the drill cuttings, and is forever lostxe2x80x94overboard, if on an offshore rig.
Moreover, every time the closed-loop designed drilling fluid syStem""s filter/screen FS is cleaned to unclog such filter/screen FS, valuable polymers are forever lost. For example, the DRISPAC Polymer costs approximately $130.00 for a 50 lb. sack and the XCD Polymer costs approximately $125.00 for a 25 lb. sack. When drilling, a 2000 ft. wellbore hole section, it is common to use 500 barrels (42 gallons per barrel) of a water-based drilling fluid requiring 750 lbs. (1.5 pounds/barrel) of the DRISPAC Polymer and 250 lbs. (0.5 pounds/barrel) of the XCD Polymer.
Several devices have been patented which are aimed at mixers, blenders and grinders.
U.S. Pat. No. 2,240,841, issued to Flynn, entitled xe2x80x9cCOMBINED MIXING AND GRINDING MILL,xe2x80x9d illustrates three stationary cutting disks having perforations and elongated slots whereby such cutting disks function to divide the mill into stages. Each stage includes a plurality of pitched circumferentially spaced blades or paddles described as thoroughly mixing the material. Each stage further includes blades or paddles to mix and feed the material and force the material through apertures in the fixed cutting disk. Moreover, the desired functions of the paddles include rotating and consequently forcing the material with great pressure through the apertures of the disks and crushing the material against the disk. On the rear side of each of the stationary cutting disks, there is a means for cutting and feeding (xe2x80x9crotary cutterxe2x80x9d). The arms of the rotary cutter cut the material in slots wherein such material also becomes crushed. However, the location of the rotary cutter having arms on the exit side of the stationary cutting disks would not eliminate the buildup of drilling fluid through the apertures.
U.S. Pat. No. 2,578,274, issued to Weigham et al., entitled xe2x80x9cMANUFACTURE OF VISCOSE,xe2x80x9d discloses, in general, forcing through a plurality of perforations formed in bases cellulose xanthate and aqueous caustic soda, which is known for the manufacturing of rayon. The Weigham et al. patent describes that for maximum disintegration, there should be the smallest practical clearance between the rotating blades and the perforating bases so that the blades exert a cutting action when forcing the xanthate-caustic soda mixture through the perforation in the bases. The blades are described as 10 to 15 thousandths of an inch above its associated grid. The blades of the Weigham et al. invention are described as having a top edge leading the bottom edge which is different from the present invention. The perforations in bases are described as xe2x85x9c of an inch, {fraction (5/16)} of an inch and {fraction (3/16)} of an inch, respectively. Moreover, the cylindrical internal diameter is 20 inches. The Weigham et al. patent passes the mixture at a rate of 38,000 lbs./hr. The Weigham et al. patent passes the mixture through the chamber with no pressure in the chambers, unlike the present invention, and the chambers are not filled to capacity, unlike the present invention. The mixture from the chamber of the Weigham et al. patent is passed to a secondary paddle tank mixture where it is slowly stirred to complete solution unlike the present invention. Thus, unlike the present invention, the Weigham et al. invention is not concerned with reducing the lumps to a non-clogging size for use in a closed-loop designed drilling fluid system or for use xe2x80x9con demandxe2x80x9d in a closed-loop designed drilling fluid system. Moreover, the Weigham et al. invention is not concerned with homogenizing drilling fluid, such as, a water-based drilling fluid, but instead is concerned with the manufacture of viscose.
U.S. Pat. No. 2,798,698, issued to Dooley, entitled xe2x80x9cCOMBINED INJECTION AND BLENDING APPARATUS,xe2x80x9d discloses three stators which include a series of perforations arranged in concentric rows which permit the passage of the liquid and the breakup of the initially mixed streams into relatively fine streams. Between the stators there are two rotors, respectively. Rotors include a plurality of spokes which have a substantially rectangular cross section. The spokes, provide sets of vanes which act as shearing elements to vigorously breakup and mix the individual streams delivered through the perforations of the stators.
U.S. Pat. No. 2,092,992, issued to Thalman, entitled xe2x80x9cEMULSIFYING APPARATUSxe2x80x9d discloses an emulsifying apparatus having a series of helical blades for effecting gyration of the material toward dispersing and grinding disks. In general, globules of immiscible fluids are readily broken up and united to form a homogeneous emulsion. A freely rotating disk and stationary disk, having apertures and apertures, respectively, formed therein function to grind the material therebetween.
U.S. Pat. No. 2,075,603, issued to Dirr, entitled xe2x80x9cMEAT GRINDER AND CUTTING KNIFE THEREFOR,xe2x80x9d U.S. Pat. No. 2,210,006, issued to Rieske, entitled xe2x80x9cFOOD GRINDING MACHINE,xe2x80x9d U.S. Pat. No. 2,505,797, Sivertsen, entitled xe2x80x9cMEAT CHOPPER,xe2x80x9d U.S. Pat. No. 3,971,514, issued to Martinelli et al., entitled xe2x80x9cMEAT GRINDER ATTACHMENTxe2x80x9d and U.S. Pat. No. 4,512,523, issued to Higashimoto, entitled xe2x80x9cAPPARATUS FOR MINCING FROZEN MEAT INTO GROUND MEATxe2x80x9d disclose, in general, meat grinders having helically-shaped or screw-shaped members in at least one chamber for transporting the meat to a rotary cutter or knife in relative close proximity to an apertured baffle wall. In general, the grinding is achieved by the passage of the meat through the apertures in the baffle wall.
U.S. Pat. No. 4,874,248, issued to Luetzelschwab, entitled xe2x80x9cAPPARATUS AND METHOD FOR MIXING A GEL AND LIQUIDxe2x80x9d discloses a low viscosity liquid, such as a monomer, which is mixed with a gel. The gel and monomer flow through a cylinder containing spaced rotating discs and stationary discs mounted between the rotating discs. The apertures in the discs pass therethrough the liquid and gel, breaking down the gel into small particles.
As can be appreciated, there exists a continuing need for a homogenizer which mixes and homogenizes drilling fluid so that upon inspection the slim-like strings are significantly reduced, if not eliminated, and globs of undissolved polymer granules which are, typically, of the fluid loss polymer, are reduced to a non-clogging glob size sufficiently smaller than the pores of the closed-loop designed drilling fluid system""s filter/screen FS. Since the slim-like strings are essentially eliminated, the other particulate matter within the homogenized drilling fluid is more evenly distributed therein.
There exists a continuing need for a homogenizer which is capable of homogenizing the drilling fluid and dissolving the polymers of the drilling fluid with little or no waste of undissolved polymers; eliminating the problematic xe2x80x9cfish eyesxe2x80x9d usually visible at the shakers; providing a homogenized drilling fluid which includes particles or globs having a size sufficiently less than the pores of the filter/screen FS so that the drilling fluid is otherwise non-clogging when flowing though the closed-loop designed drilling fluid system; and, providing on demand availability of non-clogging homogenized drilling fluid for use in drilling operations.
There is a continuing need for a homogenizer which creates non-clogging homogenized drilling fluid in an effort to maximize the reclamation of the drilling fluid; eliminate halting of the drilling operations due to a clogged filter/screen FS; eliminate and/or reduce the need for and cost of transporting an initial preprocessed load of drilling fluid to the offshore drilling rig; and, enhance the drilling fluid formula and thus its properties by maximizing the percentage of the dissolved polymers suspended in the non-clogging homogenized drilling fluid.
As will be seen more fully below, the present invention is substantially different in structure, methodology and approach from that of the prior mixers, blenders and grinders.
The preferred embodiment of the homogenizer of the present invention solves the aforementioned problems in a straight forward and simple manner.
Broadly, what is provided is an open-loop drilling fluid homogenizer for use in a closed-loop designed drilling fluid system comprising: a fluid inlet adapted to receive a water-based drilling fluid; an expanded tubular pipe portion coupled to said fluid inlet; homogenizing means housed in said expanded tubular pipe portion, for homogenizing, under pressure, in an open-loop process said water-based drilling fluid having suspended therein globs of undissolved polymer granules for creating a non-clogging homogenized water-based drilling fluid having substantially all glob sizes of said globs of undissolved polymer granules less than or equal to a predetermined non-clogging glob size; and, a fluid outlet coupled to said expanded tubular pipe portion adapted to output said non-clogging homogenized water-based drilling fluid.
In an alternate embodiment, what is provided is a drilling fluid homogenizer for homogenizing drilling fluid comprising: a chamber having a fluid inlet and a fluid outlet; and, a plurality of homogenizing classifying stages in series fluid communication in said chamber. Each homogenizing classifying stage comprises: homogenizing means for homogenizing said drilling fluid; a classifying filtering means for classifying the filtering of the homogenized drilling fluid to create classified filtered homogenized drilling fluid, and a shearing means having a minimum clearance with said filtering means for shearing said drilling fluid. The classifying filtered homogenized drilling fluid of said filtering means of a last homogenizing classifying stage is a non-clogging homogenized drilling fluid.
In view of the above, an object of the present invention is to provide a homogenizer which is capable of homogenizing the drilling fluid and dissolving the polymers of the drilling fluid with little or no waste of undissolved polymers; eliminating the problematic xe2x80x9cfish eyesxe2x80x9d usually visible at the shakers; providing a homogenized drilling fluid which includes particles or globs having a size sufficiently less than the pores of the closed-loop designed drilling fluid system""s filter/screen so that the drilling fluid is otherwise non-clogging when flowing though the closed-loop designed drilling fluid system; and, providing on demand availability of non-clogging homogenized drilling fluid for use in drilling operations.
Another object of the present invention is to provide a homogenizer which mixes and homogenizes drilling fluid so that upon inspection the slim-like strings are significantly reduced, if not eliminated, and globs of undissolved polymer granules which are, typically, of the fluid loss polymer, are reduced to a non-clogging glob size sufficiently smaller than the pores of the filter/screen. Since the slim-like strings are essentially eliminated, the other particulate matter within the homogenized drilling fluid is more evenly distributed therein.
A further object of the present invention is to provide a homogenizer which creates non-clogging homogenized drilling fluid in an effort to maximize the reclamation of the non-clogging homogenized drilling fluid; eliminate halting of drilling operations due to a clogged filter/screen of the closed-loop designed drilling fluid system; eliminate and/or reduce the need for and cost of transporting an initial pre-processed load of drilling fluid to the offshore drilling rig; and, enhance the drilling fluid formula and thus its properties by maximizing the percentage of the dissolved polymers suspended in the non-clogging homogenized drilling fluid.
A further object of the invention is to provide a homogenizer with a filtering baffle wall and a shearing propeller or shearing means having a minimum clearance with the filtering baffle wall to counter-react to the resiliently deforming and resiliently resealing capabilities of the globs of undissolved polymer granules, which are resisting filtering and, thus, to nullify the tendency of the drilling fluid to buildup, obstruct or clog the filtering baffle wall.
It is a still further object of the invention to provide a homogenizer with a relatively thin filtering baffle wall to eliminate clogging of the drilling fluid within the bored filtering channels of the filtering baffle wall.
It is a still further object of the present invention to provide a homogenizer with a shearing propeller or shearing means having a plurality of pitched radial blades wherein the pitch of the radial blade serves to direct the drilling fluid in a direction counter to the flow of the drilling fluid and thus away from the filtering baffle wall.
It is a still further object of the present invention to provide a homogenizer with a plurality of homogenizing stages in series which are in fluid communication and each of which are separated by such a filtering baffle wall to create a plurality of homogenizing classifying stages.
It is a still further object of the present invention to provide a homogenizer with a plurality of homogenizing stages wherein each stage maximizes the counter-reaction to resiliently deforming and rapidly resealing capabilities of the globs of undissolved polymer granules to penetrate the globs and thus unseal and dissolve at least part of the undissolved polymer granules.
It is a still further object of the present invention to provide a homogenizer with a plurality of homogenizing stages wherein each stage maximizes the counter-reaction to the deforming capability of slim-like strings within the drilling fluid.
It is a still further object of the present invention to provide each homogenizing classifying stage with a cutting means and a shearing means wherein the shearing means has a minimum clearance with the filtering baffle wall.
It is a still further object of the present invention to provide each homogenizing stage with a means for creating turbulence to minimize, if not prevent, binding or coalescing of the globs of undissolved polymer granules within each homogenizing classifying stage.
It is a still further object of the present invention to provide a homogenizer which is essentially an expanded tubular pipe portion having a plurality of homogenizing classifying stages for homogenizing the drilling fluid in an open loop process and which is placed in series with the holding tank and the active tank of the closed-loop designed drilling fluid system.
It is a still further object of the present invention to provide a homogenizer which homogenizes drilling fluid rapidly to a non-clogging state without recycling of the drilling fluid through the homogenizer.
It is a still further object of the present invention to provide a homogenizer which is adapted to homogenize all drilling fluid formulas including water-based drilling fluids and synthetic or oil-based drilling fluids.
A still further object of the present invention is to provide a method which provides an open-loop process for providing a sufficiently high throughput for on demand availability of non-clogging homogenized drilling fluid to a drilling unit.
Broadly, what is further provided is a method of homogenizing drilling fluid, having globs of undissolved polymer granules having clogging glob sizes and other additives, in an open-loop process for providing non-clogging homogenized drilling fluid to use in a closed-loop designed drilling fluid system, said method including the steps of: (1) homogenizing said drilling fluid to create homogenized drilling fluid and to reduce said clogging glob sizes; (2) filtering a flow of said homogenized drilling fluid to create said non-clogging homogenized drilling fluid having globs of a non-clogging glob size when flowing in said closed-loop designed drilling fluid system; and, (3) during the step of (2), shearing said globs of said undissolved polymer granules having said clogging glob sizes suspended in said flow of said homogenized drilling into said globs of said non-clogging glob size.
Broadly, what is still further provided is a method of drilling a wellbore hole using a closed-loop designed drilling fluid system wherein said closed-loop designed drilling fluid system includes at least one holding fluid tank, at least one active fluid tank, a drilling fluid pumping station, and at least one reclamation fluid tank; and a drilling unit coupled in series with said closed-loop designed drilling fluid system, said method including the steps of: (1) creating a drilling fluid source in a holding fluid tank having clogging properties wherein said drilling fluid source includes clogging glob sizes of globs of undissolved polymer granules and other additives; and, (2) providing a supply of said drilling fluid source from said holding fluid tank at a flow rate to a drilling fluid homogenizer. In said drilling fluid homogenizer, the steps of (3) homogenizing the drilling fluid source to create homogenized drilling fluid and to reduce said clogging glob sizes; (4) filtering a flow of said homogenized drilling fluid to create said non-clogging homogenized drilling fluid having globs of a non-clogging glob size when flowing through said pumping station; and, (5) during the step of (4), shearing said globs of said undissolved polymer granules having said clogging glob sizes suspended in said flow of said homogenized drilling fluid into said globs of said non-clogging glob size; (6) filling an active fluid tank with said non-clogged homogenized drilling fluid. In said closed-loop designed drilling fluid system, performing the steps of (7) providing the non-clogged homogenized drilling fluid to said drilling unit; and, (8) drilling said wellbore hole with said drilling unit using said non-clogged homogenized drilling fluid.
Broadly, what is still further provided is a method of maximizing counter-reaction to resiliently deforming and rapidly resealing capabilities of globs of undissolved polymer granules in a drilling fluid to dissolve said undissolved polymer granules, the method including the steps of: (1) cutting said drilling fluid to counter-react to said resiliently deforming and rapidly resealing capabilities of said globs of said undissolved polymer granules suspended in said drilling fluid; (2) during the cutting of step (1), penetrating at least one glob of said globs to dissolve at least some of said undissolved polymer granules of said at least one glob; (3) filtering a flow of said drilling fluid to create filtered drilling fluid having a predetermined glob size limit; and, (4) shearing said globs of said undissolved polymer granules suspended in said flow of said drilling fluid into globs of the predetermined glob size limit.
In view of the above, an object of the present invention is to provide a method of homogenizing drilling fluid and a method of drilling a wellbore hole which are capable of supplying a source of drilling fluid without any need for recycling and minimizing all globs to a predetermined minimum size significantly smaller than the closed-loop designed drilling fluid system""s filter/screen to eliminate any buildup or clogging. Thereby, the loss of revenue for stopped drilling operations for a clogged filter/screen from undissolved drilling fluid or unavailable supply of drilling fluid is significantly minimized, if not, eliminated.
In view of the above objects, it is a feature of the present invention to provide a drilling fluid homogenizer which is simple to manufacture.
Another feature of the present invention is to provide a drilling fluid homogenizer which is relatively simple structurally.
A further feature of the present invention is the production of non-clogging drilling fluid at a continuous rate of 5000-6000 gallons/hr.
A still further feature of the present invention is the production of non-clogging drilling fluid at a continuous rate of 17,000 to 21,000 gallons/hr.
A still further feature of the present invention is that the non-clogging glob sizes are sufficiently smaller than apertures of a closed-loop designed drilling fluid system""s filter/screen in the pumping station which pumps drilling fluid to the drilling unit.
A still further feature of the present invention is to provide a high throughput of non-clogging homogenized drilling fluid which has an increased percentage of dissolved polymers for a given drilling fluid formula.
An advantage of the present invention is that the non-clogging homogenized drilling fluid minimizes halting of drilling operations and, thus, reduces the costs associated with drilling a wellbore hole.
A further advantage of the present invention is that the non-clogging homogenized drilling fluid maximizes the ability of the closed-loop designed drilling fluid system to recover the non-clogging homogenized drilling fluid flowing from the wellbore hole.
A still further advantage of the present invention is that the increased percentage of dissolved polymers in the drilling fluid formula simplifies overall drilling fluid engineering.
A still further advantage of the present invention is that the increased percentage of dissolved polymers in the drilling fluid formula increases the integrity of the drilling fluid formula to perform its major functions during drilling operation.
The above and other objects, features and advantages of the present invention will become apparent from the drawings, the description given herein, and the appended claims.